Dual Angle Research Articles

A compact dual bevel planar monopole antenna with lumped element for ultra high frequency/very high frequency application

AbstractA novel small size planar monopole antenna operating from 0.1 to 1100 MHz is proposed. A planar monopole antenna constructed with 148 mm × 64 mm of radiating element and 80 mm square of ground plane is suitable for cognitive radio (CR) applications where it can cover a very high frequency and a partial of ultra high frequency (UHF) band for spectrum sensing. The proposed monopole antenna is designed by combining a beveling technique and resistor lumped element loading by employing FR4 substrate for low‐cost intention. The integration of the resistor with double bevel contributes to the behavior of an inductor as more current are excited to the ground eventually making the radiating element becomes more magnetic. Furthermore, it is found that 50° of dual bevel angle give optimization results for the impedance bandwidth of the antenna. As a result, the low frequency has shifted to the left and enhanced the antenna's impedance bandwidth significantly from 2.2:1 (103%) to 11:1 (200%). The proposed antenna is also extensively proficient in producing divisive radiation patterns with vertical polarization at four different frequencies; 200, 500, 800, and 1000 MHz. The presented antenna performances clarify the potential of the approach between simulation and the measurement results. Instead of CR, the proposed antenna has attractive potentials to be used for GSM, broadcasting, UHF radio frequency identification (RFID) and radio astronomy applications in the future. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:156–160, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26515

Cartilage quality in rheumatoid arthritis: comparison of T2* mapping, native T1 mapping, dGEMRIC, ΔR1 and value of pre-contrast imaging

To prospectively evaluate four non-invasive markers of cartilage quality--T2* mapping, native T1 mapping, dGEMRIC and ΔR1--in healthy volunteers and rheumatoid arthritis (RA) patients. Cartilage of metacarpophalangeal (MCP) joints II were imaged in 28 consecutive subjects: 12 healthy volunteers [9 women, mean (SD) age 52.67 (9.75) years, range 30-66] and 16 RA patients with MCP II involvement [12 women, mean (SD) age 58.06 (12.88) years, range 35-76]. Sagittal T2* mapping was performed with a multi-echo gradient-echo on a 3 T MRI scanner. For T1 mapping the dual flip angle method was applied prior to native T1 mapping and 40 min after gadolinium application (delayed gadolinium-enhanced MRI of cartilage, dGEMRIC, T1(Gd)). The difference in the longitudinal relaxation rate induced by gadolinium (ΔR1) was calculated. The area under the receiver operating characteristic curve (AROC) was used to test for differentiation of RA patients from healthy volunteers. dGEMRIC (AUC 0.81) and ΔR1 (AUC 0.75) significantly differentiated RA patients from controls. T2* mapping (AUC 0.66) and native T1 mapping (AUC 0.66) were not significantly different in RA patients compared to controls. The data support the use of dGEMRIC for the assessment of MCP joint cartilage quality in RA. T2* and native T1 mapping are of low diagnostic value. Pre-contrast T1 mapping for the calculation of ΔR1 does not increase the diagnostic value of dGEMRIC.

On Closed Ruled Surfaces Concerned with Dual Frenet and Bishop Frames

In this paper; the pitch, the angle of pitch and the dual angle of pitch of ruled surface in ℝ3 which is corresponded to a closed curve on dual unit sphere are investigated. This closed curve is formed by the vectors of Frenet and Bishop frame of a closed curve on dual unit sphere. Also the relation between dual angle of pitch and pitch, angle of pitch is obtained.

T₁-corrected fat quantification using chemical shift-based water/fat separation: application to skeletal muscle.

Chemical shift-based water/fat separation, like iterative decomposition of water and fat with echo asymmetry and least-squares estimation, has been proposed for quantifying intermuscular adipose tissue. An important confounding factor in iterative decomposition of water and fat with echo asymmetry and least-squares estimation-based intermuscular adipose tissue quantification is the large difference in T(1) between muscle and fat, which can cause significant overestimation in the fat fraction. This T(1) bias effect is usually reduced by using small flip angles. T(1) -correction can be performed by using at least two different flip angles and fitting for T(1) of water and fat. In this work, a novel approach for the water/fat separation problem in a dual flip angle experiment is introduced and a new approach for the selection of the two flip angles, labeled as the unequal small flip angle approach, is developed, aiming to improve the noise efficiency of the T(1) -correction step relative to existing approaches. It is shown that the use of flip angles, selected such the muscle water signal is assumed to be T(1) -independent for the first flip angle and the fat signal is assumed to be T(1) -independent for the second flip angle, has superior noise performance to the use of equal small flip angles (no T(1) estimation required) and the use of large flip angles (T(1) estimation required).

Motion correction improves image quality of dGEMRIC in finger joints

To assess motion artifacts in dGEMRIC of finger joints and to evaluate the effectiveness of motion correction. In 40 subjects (26 patients with finger arthritis and 14 healthy volunteers) dGEMRIC of metacarpophalangeal joint II was performed. Imaging used a dual flip angle approach (TE 3.72 ms, TR 15 ms, flip angles 5° and 26°). Two sets of T1 maps were calculated for dGEMRIC analysis from the imaging data for each subject: one with and one without motion correction. To compare image quality, visual grading analysis and precision of dGEMRIC measurement of both dGEMRIC maps for each case were evaluated. Motion artifacts were present in 82% (33/40) of uncorrected dGEMRIC maps. Motion artifacts were graded as severe or as rendering evaluation impossible in 43% (17/40) of uncorrected dGEMRIC maps. Motion corrected maps showed significantly less motion artifacts (P<0.001) and were graded as evaluable in 97% (39/40) of cases. Precision was significantly higher in motion corrected images (coefficient of variation (CV=.176±.077), compared to uncorrected images (CV .445±.347) (P<.001). Motion corrected dGERMIC was different in volunteers and patients (P=.044), whereas uncorrected dGEMRIC was not (P=.234). Motion correction improves image quality, dGEMRIC measurement precision and diagnostic performance in dGEMRIC of finger joints.

Feasibility of Texture Analysis for the Assessment of Biochemical Changes in Meniscal Tissue on T1 Maps Calculated From Delayed Gadolinium-Enhanced Magnetic Resonance Imaging of Cartilage Data

To (1) establish the feasibility of texture analysis for the in vivo assessment of biochemical changes in meniscal tissue on delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC), and (2) compare textural with conventional T1 relaxation time measurements calculated from dGEMRIC data ("T1(Gd) relaxation times"). We enrolled 10 asymptomatic volunteers (7 men and 3 women; mean age, 27.2 +/- 4.5 years), without a history of meniscus damage, in our study. MRI of the right knee was performed at 3.0 T. An isotropic, 3-dimensional (3D), double-echo steady-state sequences was used for morphologic evaluation, and a dual flip angle 3D gradient echo sequence was used for T1(Gd) mapping. All MRI scans were performed 90 minutes after injection of 0.2 mmol/kg of Gd-diethylenetriamine pentaacetic acid (DTPA), and subsequently, during application of a compressive force (50% of the body weight) in the axial direction. Regions of interest, covering the central portions of the posterior horn of the medial meniscus, were defined on 3 adjacent sagittal sections. Based on the relaxation time maps, mean T1(Gd), as well as the T1(Gd) texture features derived from the co-occurrence matrix (COC: Angular Second Moment, Entropy, Inverse Difference Moment) and wavelet transform (WAV: WavEnLL, WavEnHL, WavEnHH, WavEnLH), were calculated. Paired t tests were used to assess differences between baseline and compression, and intraclass correlation coefficients (ICC) were calculated to establish the intrarater reliability of the measurements. Mean T1(Gd) (-67.3 ms, P = 0.011), Angular Second Moment (-0.0002, P = 0.009), Entropy (+0.033, P = 0.025), WavEnLL (+1011.16, P = 0.002), WavEnHL (+18.64, P = 0.012), and WavEnLH (+72.74, P = 0.035) differed significantly between baseline and compression. Intrarater reliability was substantial for mean T1(Gd) relaxation times (ICC = 0.99-1.0), and also for T1(Gd) co-occurrence matrix (ICC = 0.63-0.92) and WAV (ICC = 0.86-0.98) features. Texture features extracted from T1 maps calculated from dGEMRIC data are feasible for the in vivo assessment of biochemical changes in the menisci, such as might be induced by mechanical loading. Thus, T1(Gd) texture features complement conventional relaxation time measurements. Further studies are necessary to determine whether the mechanical compression, or a prolonged Gd-DTPA uptake, or both, are responsible for the observed decrease in mean T1(Gd) relaxation times in the menisci.

Exact algebraization of the signal equation of spoiled gradient echo MRI

The Ernst equation for Fourier transform nuclear magnetic resonance (MR) describes the spoiled steady-state signal created by periodic partial excitation. In MR imaging (MRI), it is commonly applied to spoiled gradient-echo acquisition in the steady state, created by a small flip angle α at a repetition time TR much shorter than the longitudinal relaxation time T1. We describe two parameter transformations of α and TR/T1, which render the Ernst equation as a low-order rational function. Computer algebra can be readily applied for analytically solving protocol optimization, as shown for the dual flip angle experiment. These transformations are based on the half-angle tangent substitution and its hyperbolic analogue. They are monotonic and approach identity for small α and small TR/T1 with a third-order error. Thus, the exact algebraization can be readily applied to fast gradient echo MRI to yield a rational approximation in α and TR/T1. This reveals a fundamental relationship between the square of the flip angle and TR/T1 which characterizes the Ernst angle, constant degree of T1-weighting and the influence of the local radio-frequency field.

Template-Based $B _{1}$ Inhomogeneity Correction in 3T MRI Brain Studies

Low noise, high resolution, fast and accurate T₁ maps from MRI images of the brain can be performed using a dual flip angle method. However, B₁ field inhomogeneity, which is particularly problematic at high field strengths (e.g., 3T), limits the ability of the scanner to deliver the prescribed flip angle, introducing errors into the T₁ maps that limit the accuracy of quantitative analyses based on those maps. A dual repetition time method was used for acquiring a B₁ map to correct that inhomogeneity. Additional inaccuracies due to misregistration of the acquired T₁-weighted images were corrected by rigid registration, and the effects of misalignment on the T₁ maps were compared to those of B₁ inhomogeneity in 19 normal subjects. However, since B₁ map acquisition takes up precious scanning time and most retrospective studies do not have B₁ map, we designed a template-based correction strategy. B₁ maps from different subjects were aligned using a twelve-parameter affine registration. Recomputed T₁ maps showed an important improvement with respect to the noncorrected maps: histograms of all corrected maps exhibited two peaks corresponding to white and gray matter tissues, while unimodal histograms were observed in all uncorrected maps because of the inhomogeneity. A method to detect the best nonsubject-specific B₁ correction based on a set of features was designed. The optimum set of weighting factors for those features was computed. The best available B₁ correction was detected in almost all subjects while corrections comparable to the T₁ map corrected using the B₁ map from the same subject were detected in the others.

Snow permittivity retrieval inversion algorithm for estimating snow wetness

The environmental satellite (ENVISAT) advanced synthetic aperture radar (ASAR) offers the opportunity for monitoring snow parameters with dual polarization and multi-incidence angle. Snow wetness is an important index for indicating snow avalanche, snowmelt runoff modelling, water supply for irrigation and hydropower stations, weather forecasts and understanding climate change. We used a first-order scattering model that includes both volume and air/snow surface scattering based on a developed inversion model to estimate snow dielectric constant, which can be further related for estimating snow wetness. Comparison with field measurement showed that the correlation coefficient for snow permittivity estimated from ASAR data was observed to be 0.8 at 95% confidence interval and model bias was observed as 2.42% by volume at 95% confidence interval. The comparison of ASAR-derived snow permittivity with ground measurements shows the average absolute error 2.5%. The snow wetness range varies from 0 to 15% by volume.

Delayed gadolinium‐enhanced MRI of cartilage in the ankle at 3 T: Feasibility and preliminary results after matrix‐associated autologous chondrocyte implantation

To demonstrate the feasibility of delayed gadolinium-enhanced magnetic resonance imaging (MRI) of cartilage (dGEMRIC) in the ankle at 3 T and to obtain preliminary data on matrix associated autologous chondrocyte (MACI) repair tissue. A 3D dual flip angle sequence was used with an eight-channel multipurpose coil at 3 T to obtain T1 maps both pre- and postintravenous contrast agent (Magnevist, 0.2 mM/kg). Postcontrast T1 over time was evaluated in three volunteers; a modified dGEMRIC protocol was then used to assess 10 cases after MACI in the ankle. Forty-five minutes were found sufficient for maximum T1 decrease. MACI cases had a precontrast mean T1 of 1050 +/- 148.4 msec in reference cartilage (RC) and 1080 +/- 165.6 msec in repair tissue (RT). Postcontrast T1 decreased to 590 +/- 134.0 msec in RC and 554 +/- 133.0 msec in RT. There was no significant difference between the delta relaxation rates in RT (9.44 x 10(-4) s(-1)) and RC (8.04 x 10(-4) s(-1), P = 0.487). The mean relative delta relaxation rate was 1.34 +/- 0.83. It is feasible to assess the thin cartilage layers of the ankle with dGEMRIC at 3 T; MACI can yield RT with properties similar to articular cartilage.

Simultaneous B0‐ and B1+‐Map acquisition for fast localized shim, frequency, and RF power determination in the heart at 3 T

High-field (>or=3 T) cardiac MRI is challenged by inhomogeneities of both the static magnetic field (B(0)) and the transmit radiofrequency field (B(1)+). The inhomogeneous B fields not only demand improved shimming methods but also impede the correct determination of the zero-order terms, i.e., the local resonance frequency f(0) and the radiofrequency power to generate the intended local B(1)+ field. In this work, dual echo time B(0)-map and dual flip angle B(1)+-map acquisition methods are combined to acquire multislice B(0)- and B(1)+-maps simultaneously covering the entire heart in a single breath hold of 18 heartbeats. A previously proposed excitation pulse shape dependent slice profile correction is tested and applied to reduce systematic errors of the multislice B(1)+-map. Localized higher-order shim correction values including the zero-order terms for frequency f(0) and radiofrequency power can be determined based on the acquired B(0)- and B(1)+-maps. This method has been tested in 7 healthy adult human subjects at 3 T and improved the B(0) field homogeneity (standard deviation) from 60 Hz to 35 Hz and the average B(1)+ field from 77% to 100% of the desired B(1)+ field when compared to more commonly used preparation methods.

Liver fat quantitation at 3T using a single breath hold multi-echo sequence

Purpose: Magnetic resonance imaging and spectroscopy provide a tool for fat quantitation for a wide range of liver conditions such as steatosis, non alcoholic fatty liver disease (NAFL), or non alcoholic steatohepatitis (NASH). Various methods are being used for fat quantitation, such as MR spectroscopy or 3-point Dixon. A practical method based on dual flip angle and in-phase and out-of-phase (IP-OP) echoes has been developed on 1.5T [1] and validated at 3T [2]. The method consisted of 3 distinct scans: a high flip angle (70°) and low flip angle (20°) in- and out-of-phase gradient echo sequences, followed by another T2 weighted dual-echo gradient echo scan for T2* measurement. Here we present an improvement of the method, where we acquired 6 echoes (3 in-phase/out-of-phase pairs) with dynamically varying flip angle, providing fat quantitation and T2* correction in a single breath hold scan.

Transverse relaxation time (T2) mapping in the brain with off‐resonance correction using phase‐cycled steady‐state free precession imaging

To investigate a new approach for more completely accounting for off-resonance affects in the DESPOT2 (driven equilibrium single pulse observation of T(2)) mapping technique. The DESPOT2 method derives T(2) information from fully balanced steady-state free precession (bSSFP) images acquired over multiple flip angles. Off-resonance affects, which present as bands of altered signal intensity throughout the bSSFP images, results in erroneous T(2) values in the corresponding calculated maps. Radiofrequency (RF) phase-cycling, in which the phase of the RF pulse is incremented along the pulse train, offers a potential method for eliminating these artifacts. In this work we present a general method, referred to as DESPOT2, with full modeling (DESPOT2-FM), for deriving T(2), as well as off-resonance frequency, from dual flip angle bSSFP data acquired with two RF phase increments. The method is demonstrated in vivo through the acquisition of whole-brain, 1 mm(3) isotropic T(2) maps at 3T and shown to provide near artifact-free maps, even in areas with steep susceptibility-induced gradients. DESPOT2-FM offers an efficient method for acquiring high spatial resolution, whole-brain T(2) maps at 3T with high precision and free of artifact.

Delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) of cadaveric shoulders: Comparison of contrast dynamics in hyaline and fibrous cartilage after intraarticular gadolinium injection

Delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) is a novel method to investigate cartilaginous and fibrocartilaginous structures. To investigate the contrast dynamics in hyaline and fibrous cartilage of the glenohumeral joint after intraarticular injection of gadopentetate dimeglumine. Transverse T(1) maps were acquired on a 1.5T scanner before and after intraarticular injection of 2.0 mmol/l gadopentetate dimeglumine in five cadaveric shoulders using a dual flip angle three-dimensional gradient echo (3D-GRE) sequence. The acquisition time for the T(1) maps was 5 min 5 s for the whole shoulder. Measurements were repeated every 15 min over 2.5 hours. Regions of interest (ROIs) covering the glenoid cartilage and the labrum were drawn to assess the temporal evolution of the relaxation parameters. T(1) of unenhanced hyaline cartilage of the glenoid was 568+/-34 ms. T(1) of unenhanced fibrous cartilage of the labrum was 552+/-38 ms. Significant differences (P=0.002 and 0.03) in the relaxation parameters were already measurable after 15 min. After 2 to 2.5 hours, hyaline and fibrous cartilage still demonstrated decreasing relaxation parameters, with a larger range of the T(1)(Gd) values in fibrous cartilage. T(1) and triangle Delta R(1) values of hyaline and fibrous cartilage after 2.5 hours were 351+/-16 ms and 1.1+/-0.09 s(-1), and 332+/-31 ms and 1.2+/-0.1 s(-1), respectively. A significant decrease in T(1)(Gd) was found 15 min after intraarticular contrast injection. Contrast accumulation was faster in hyaline than in fibrous cartilage. After 2.5 hours, contrast accumulation showed a higher rate of decrease in hyaline cartilage, but neither hyaline nor fibrous cartilage had reached equilibrium.

T2 mapping and dGEMRIC after autologous chondrocyte implantation with a fibrin-based scaffold in the knee: Preliminary results

Objective To assess repair tissue (RT) after the implantation of BioCart™II, an autologous chondrocyte implantation (ACI) technique with a fibrin-hyaluronan polymer as scaffold. T2 mapping and delayed Gadolinium Enhanced Magnetic Resonance Imaging of Cartilage (dGEMRIC) were used to gain first data on the biochemical properties of BioCart™II RT in vivo. Methods T2 mapping and dGEMRIC were performed at 3 T in five patients (six knee joints) who had undergone ACI 15–27 months before. T2 maps were obtained using a pixel wise, mono-exponential non-negative least squares fit analysis. For quantitative T1 mapping a dual flip angle 3D GRE sequence was used and T1 maps were calculated pre- and post-contrast using IDL software. Subsequent region of interest analysis was carried out in comparison with morphologic MRI. Results A spatial variation of T2 values in both hyaline, normal cartilage (NC) and RT was found. Mean RT T2 values and mean NC T2 values did not differ significantly. Relative T2 values were calculated from global RT and NC T2 and showed a small range (0.84–1.07). The relative delta relaxation rates (rΔR1) obtained from the T1 maps had a wider range (0.77–4.91). Conclusion T2 mapping and dGEMRIC provided complementary information on the biochemical properties of the repair tissue. BioCart™II apparently can provide RT similar to hyaline articular cartilage and may become a less-invasive alternative to ACI with a periosteal flap.

Batch and Size-Exclusion Chromatographic Characterization of Ultra-high Molar Mass Sodium Hyaluronate Containing Low Amounts of Strongly Scattering Impurities by Dual Low Angle Light Scattering/Refractometric Detection

It is shown that very pure sodium hyaluronate (HA) contains small amounts of strongly scattering impurities not detectable on mass scale by refractometric detection, but clearly detectable using low angle light scattering detection during a static bulk light scattering experiment. Size filtration of its solutions does not remove these impurities, only reduces their amount depending on filter porosity. Complete removal of these particle impurities, independent of filter porosity, is achieved by hydrophobic adsorption on hydrophobic filter membranes. Using 0.1 M NaCl as a mobile phase, size exclusion chromatography (SEC) column removes the impurities by hydrophobic adsorption as well; molar masses obtained from both techniques thus agree when hydrophobic filters are used in bulk light scattering experiments. Diverse hydrodynamic flow retardation effects including slalom chromatography behavior are shown to substantially bias molar mass distributions obtained for ultra-high molar mass (UHM) HA, unless the flow rate in SEC analysis is reduced below 0.1 mL/min. Too high injected concentration (c inj ) is shown to introduce the onset of HA on column degradation. Correct polydispersity indices and molar mass distributions of UHM HA are obtained from SEC at a flow rate of 0.09 mL/min and optimized c inj .

SU‐GG‐T‐266: Implementation of Total Skin Electron Irradiation (TSEI) Using High Dose Rate Mode at Siriraj Hospital

Purpose: To implement and commissioning of applied Stanford total skin electron irradiation (TSEI) technique using standard linear accelerator at our institute. Method and Materials: Patient was treated in six different upright patient positions using dual angle fields. This study was carried out on Varian 23EX linear accelerator with 6 MeV, 36×36 cm2 field size at collimator in HDTSe mode at a SSD of 400 cm behind a beam degrader. The dosimetric characteristics were verified experimentally using a parallel plate ion chamber, electron diodes, and TLD‐100 chip and rod types. The delivered dose is 36 Gy in 9 weeks. The basic dosimetric parameter consists of beam profile, depth dose curve and electron beam output in the treatment plane. The output and depth dose curve was measured by PTW23343 Markus chamber in solid phantom. Delivered dose from six dual fields technique in treatment position was verified on round phantom by TLD‐100. Results: The uniform vertical profile was obtained for gantry angulations of ± 17.5 degree above and below horizontal within 10% of the prescribed dose. The depth dose curve shows maximum dose at skin surface. The mean energy is 2.09 MeV with beam degrader 1 cm thick. The dose uniformity from six dual fields on round phantom is within 10%. The average measured skin dose in the anterior and posterior at the level of head, chest and pelvis on rando phantom is within 10% of prescribed point. Total X‐ray contamination in the rando phantom is about 1.35% of the delivered dose. Conclusion: The TSEI technique using six dual fields applied Stanford technique produced a uniformity at the whole patient's surface cannot be better than 15% of the prescribed dose because of variable skin distance, self‐shielding, and differences in curvature.

Dynamic contrast enhanced MRI (DCE MRI) for Phase I anti-angiogenic trial: Comparison of the transfer constant (Ktrans) to blood flow and permeability derived by a distributed parameter model

3514 Background: The distributed parameter (DP) model is a DCE-MRI model that enables derivation of blood flow and capillary permeability-surface area product (PS). We aim to compare the DP model to Ktrans in the assessment of angiogenesis assessment in a Phase I anti- angiogenic trial. Methods: Twenty-seven evaluable patients from a completed phase I trial (ABT-869) with 3 dose escalations formed the study population. All patients underwent DCE-MRI at baseline, Day 3 and Day 15 with temporal resolution of 4 seconds. Gadolinium concentrations were estimated using dual flip angle method. Ktrans, normalized IAUC60, permeability-surface area product derived from DP model (DP-PS), and blood flow derived from DP model, were calculated. Patients demonstrating progressive disease in first 2 evaluations scans (cycle 2 or 4) based on RECIST criteria were considered progressors and all other patients, non-progressors. Receiver operating curve (ROC) analysis was performed. Correlation with area under the curve extrapolated to infinity (AUCinf) was analyzed. Results: There is good correlation between DP-PS and drug exposure above threshold (threshold concentration 80 ng/mL; time threshold 3.5 hours) measured by AUCinf (Spearman's coefficient −0.556, p = 0.007). Although slightly weaker correlation is found with normalized IAUC60 (Spearman's coefficient −0.537, p = 0.01), the difference is not significant. (p = 0.9334) There is poor correlation for Ktrans (Spearman's coefficient −0.128, p = 0.570). ROC analysis for predicting progressors versus non-progressors showed a higher ROC area for DP-PS compared to Ktrans (0.869 versus 0.417, p < 0.001) and normalized IAUC60 (0.869 versus 0.643, p = 0.1543, not significant). Using a 29.45% drop from baseline at Day 15 to predict non-progressors, the sensitivity of DP-PS is 64.3% and the specificity is 100% whereas the sensitivity of Ktrans is 28.6% and the specificity is 66.7%. In 7 cases, DP-PS correctly predicted the eventual outcome whereas Ktrans predicted the direct opposite. Conclusion: Permeability-surface area product derived from DP model shows better correlation with drug exposure and may predict patient outcome better than Ktrans. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Expert Testimony Other Remuneration Abbott Laboratories Abbott Laboratories Abbott Laboratories

An Atmospheric Radiosounding Database for Generating Land Surface Temperature Algorithms

A database of global, cloud-free, and atmospheric radiosounding profiles was compiled with the aim of simulating radiometric measurements from satellite-borne sensors in the thermal infrared. The objective of the simulated data is to generate split-window (SW) and dual-angle (DA) algorithms for the retrieval of land surface temperature (LST) from Terra/Moderate Resolution Imaging Spectroradiometer (MODIS) and Envisat/Advanced Along Track Scanning Radiometer (AATSR) data. The database contains 382 radiosounding profiles acquired over land, with nearly uniform distribution of precipitable water between 0.02 and 5.5 cm. Radiative transfer calculations were performed with the MODTRAN 4 code for six viewing angles between 0deg and 60deg. The resulting radiance spectra were convoluted with the response filter functions of MODIS bands 31 and 32 and AATSR channels at 11 and 12 mum. By using the simulation database, the SW algorithms adapted for MODIS and AATSR data and the DA algorithms for AATSR data were developed. Both types of algorithms are quadratic in the brightness temperature difference and depend explicitly on the land surface emissivity. The SW and DA algorithms were validated with actual ground measurements of LST collected concurrently to MODIS and AATSR observations in a site located close to the city of Valencia, Spain, in a large, flat, and thermally homogeneous area of rice crops. The results obtained have no bias and a standard deviation around plusmn0.5 K for the SW algorithms at nadir for both sensors. The SW algorithm used in the forward view results in a bias of 0.6 K and a standard deviation of plusmn0.8 K. The worst results are obtained in the other algorithms with a bias close to -1.0 K and a standard deviation close to plusmn1.1 K in the case of the DA algorithms.

Differentiating normal hyaline cartilage from post-surgical repair tissue using fast gradient echo imaging in delayed gadolinium-enhanced MRI (dGEMRIC) at 3 Tesla

The purpose was to evaluate the relative glycosaminoglycan (GAG) content of repair tissue in patients after microfracturing (MFX) and matrix-associated autologous chondrocyte transplantation (MACT) of the knee joint with a dGEMRIC technique based on a newly developed short 3D-GRE sequence with two flip angle excitation pulses. Twenty patients treated with MFX or MACT (ten in each group) were enrolled. For comparability, patients from each group were matched by age (MFX: 37.1 +/- 16.3 years; MACT: 37.4 +/- 8.2 years) and postoperative interval (MFX: 33.0 +/- 17.3 months; MACT: 32.0 +/- 17.2 months). The Delta relaxation rate (DeltaR1) for repair tissue and normal hyaline cartilage and the relative DeltaR1 were calculated, and mean values were compared between both groups using an analysis of variance. The mean DeltaR1 for MFX was 1.07 +/- 0.34 versus 0.32 +/- 0.20 at the intact control site, and for MACT, 1.90 +/- 0.49 compared to 0.87 +/- 0.44, which resulted in a relative DeltaR1 of 3.39 for MFX and 2.18 for MACT. The difference between the cartilage repair groups was statistically significant. The new dGEMRIC technique based on dual flip angle excitation pulses showed higher GAG content in patients after MACT compared to MFX at the same postoperative interval and allowed reducing the data acquisition time to 4 min.